Description of Prior Art
Feedstreams containing C.sub.4 to C.sub.24 hydrocarbons are fractionated during the processing of crude oil. In particular, C.sub.4 feedstreams containing butadiene, isobutylene, 1-butene, cis- and trans-2-butene, butane and isobutane, are often processed to extract the butadiene leaving behind a mixture commonly referred to as Raffinate I, which typically contains isobutylene, 1-butene, cis- and trans-2-butene, n-butane and isobutane.
The Raffinate I stream is commonly used to produce polyisobutylene. Processes to produce isobutylene polymers use Lewis acid catalysts such as aluminum chloride in the presence of a number of cocatalysts, also referred to as catalyst promoters, which can include hydrogen chloride, and hydrocarbon chlorides such as isopropyl chloride, t-butyl chloride and water. Isobutylene has been polymerized using a BF.sub.3 catalyst and a cocatalyst such as water.
The remaining feedstream, after removal of the isobutylene, is commonly referred to as Raffinate II. While the specific compositions may vary, Raffinate II typically contains n-butane, isobutane, and greater than 50% by weight of a mixture of n-butene-1, and cis- and trans-2-butene, as well as minor amounts, typically less than 5%, of isobutylene. There can also be minor amounts, i.e. less than 3%, of C.sub.3 compounds. The amount of polymerizable butenes in purified Raffinate II is typically about 70% or greater. The ready supply of the Raffinate II feedstream makes it desirable to convert the Raffinate II, and particularly the 1- and 2-butenes in the Raffinate II, to useful products.
While attempts have been made over the years to generate polymers from n-butenes, limitations in the ability to process and polymerize n-butenes have limited their use. Generally, n-butenes have been polymerized using Ziegler-Natta type catalysts as well as Friedel-Crafts catalysts. Polymers made by using Ziegler-Natta catalysts are generally stereoregular. In particular, polymers such as poly(1-butene) are known to be polymerized using Ziegler-Natta catalysts to form stereoregular structures which leads to a crystalline polymer.
In contrast, cationic polymerization results in a head to tail addition of monomer in a random or atactic configuration which leads to an amorphous polymer. Disclosed Lewis acid and Friedel-Crafts catalysts include AlCl.sub.3, AlBr.sub.3, BF.sub.3, SnCl.sub.4, H.sub.2 SO.sub.4 and other strong acids.
Fontana et al., Catalyzed Polymerization of Monoalkylethylenes, Industrial and Engineering Chemistry, Volume 44, No. 7, pg. 1688 -1695 (received for view Oct. 6, 1951, accepted Mar. 5, 1952) reviews the polymerization of olefins by means of Friedel-Craft catalysts including aluminum bromide. The continuous polymerization of 1-butene is reviewed beginning at page 1691. Polymerization temperatures varied from -50.degree. C. to 0.degree. C. with optimum results obtained at about -35.degree. C. A correlation between molecular weight, viscosity and thickening power is presented. A correlation of molecular weight and thickening power is also presented. A reported molecular weight of poly(1 butene) of 1,120,000 was obtained by a single determination using light scattering.
Fontana et al., High Molecular Weight Polymers From Propylene and 1-butene, Industrial and Engineering Chemistry, Volume 44, No. 12, pg. 2955-2962, December 1952, is a continuation of the above paper. This paper addresses the possibility that molecular weight was limited due to the removal of short chains from the reaction zone before they had sufficient time to grow to their full extent. An attempt was made to slow the growth of many polymer molecules in the reaction mixture. This was accomplished by using a semi-batch method to fully utilize the catalyst and the promoter and prevent tar formation by initiating the reaction under conditions simulating those used in the continuous method. Thickening power was used as an indicia of molecular weight.
U.S. Pat. No. 2,571,354 discloses polymerizing monoalkylethylenes in the presence of dissolved aluminum bromide catalyst and catalyst promoter under conditions of low instantaneous concentration of unpolymerized olefin and free olefin followed by conditions conducive to maximum growth of the polymer chains. The polymer is obtained by simultaneous mixing of monoalkylethylene and aluminum bromide solution in the presence of a catalyst promoter to produce polymerization mixture as a first step. In the second step, monoalkylethylene is slowly added to the polymerization mixture. By conducting the polymerization of monoalkylethylenes in this manner, polymer products of higher viscosities were obtained. It is postulated that the combination of low instantaneous concentrations of unpolymerized olefin and catalyst in the first step and the opportunity for polymer chains to grow in the second step, provides conditions for the production of high viscosity polymers having improved temperature-viscosity characteristics. The high viscosity polymers are disclosed to have comparatively low molecular weights.
U.S. Pat. No. 2,521,939 discloses the polymerization of olefins with a metal halide catalyst which can include aluminum bromide and a hydrogen bromide promoter. The polymerization process is directed to any type of olefin where hydrogen bromide promoter can be employed. Such processes include the polymerization of polypropylene, 1-butene, 2-butene, the isomeric pentenes, hexenes, etc. Other disclosed processes include the polymerization of diolefins, the copolymerization of two dissimilar monoolefins such as the copolymerization of propylene and a butene, or the interpolymerization of a monoolefin with a diolefin. The goal of this patent is to increase the viscosity of the olefin polymer products by removing impurities introduced with the hydrogen bromide promoter. The impurities are speculated to decrease the viscosity of the polymer products.
U.S. Pat. No. 2,525,787 discloses the polymerization of propylene to produce polymers having small changes in viscosity with changes in temperature. The process obtains high yields by contacting propylene with aluminum bromide dissolved in a non-polymerizing hydrocarbon solvent in the absence of a catalyst promoting agent. The aluminum bromide may be dissolved by stirring the solid compound with a saturated hydrocarbon solvent. Because solid aluminum bromide is difficult to handle and to dissolve, it is preferred to affect solution by melting. The aluminum bromide is heated to a temperature of about 98.degree. C. or higher and thereafter mixed with the solvent while in a molten state. In batch processes the polymer is fed to a reactor containing dissolved aluminum bromide plus promoter. In continuous operation, dissolved aluminum bromide is fed to a reactor separately from the catalyst and the promoter. The catalyst is fed to the reactor and the hydrogen bromide is fed to the system through a line connected to the catalyst feed line upon entering the reactor.
U.S. Pat. No. 2,525,788 is directed to mineral oil lubricants containing polymers of 1-olefins including 1-butene. The 1-olefins containing 4 or more carbon atoms are polymerized in high yield. The disclosed process comprises contacting the olefin with aluminum bromide catalyst dissolved in a non-polymerizing hydrocarbon solvent in the presence of a catalyst-promoting agent under selected reaction conditions. The ratio of promoter to aluminum bromide catalyst is considered to be significant. Preferably, the ratio is between about 0.08 and 1.2 moles of catalyst promoter per mole of aluminum bromide catalyst. It was discovered that high thickening power polymers are obtained when the instantaneous 1-olefin monomer concentration in the reaction mixture is maintained at a low value. The rate of addition of 1-olefin should not be greater than 4.0 moles per mole of aluminum bromide catalyst per minute. Another significant variable is the olefin to catalyst ratio, which is disclosed to be in excess of 5 moles of olefin per mole of aluminum bromide catalyst. It is desirable to employ the 1-olefins as free as possible of isoparaffins, olefins containing two alkyl groups on the carbon atom once removed from the terminal carbon atoms, and 2-olefins, since the presence of these compounds tends to reduce the thickening power in the relative thickening power of the polymer product.
U.S. Pat. No. 2,657,246 discloses the polymerization of isobutylene at from -40.degree. F. to 120.degree. F. using a Friedel-Crafts type catalyst which can include aluminum chloride or aluminum bromide. There is disclosed a polymer product having a narrow range of high viscosity and high viscosity index with a molecular weight below 4000 Staudinger.
U.S. Pat. No. 2,678,957 is directed to the polymerization of polypropylene, butene-1, pentene-1, hexene-1, octene-1, decene-1, dodecene-1, and octadecene-1 as examples of monoalkylethylenes. It is disclosed that polymers of propylene, butene-1 and pentene-1 can be derived from C.sub.3, C.sub.4 and C.sub.5 refinery streams respectively. Mixtures of monoalkylethylenes can also be used. An aluminum bromohalide catalyst system is used to make high viscosity polymers including poly-1-butene. However, when polymer products having relatively high thickening powers are desired, it is disclosed that the monoalkylethylene reactants must be substantially free of isoparaffins, 1-olefins having two alkyl groups on a carbon adjacent to the double bond, and/or olefins other than 1-olefins. The presence of these hydrocarbons tends to reduce the thickening power and the relative thickening power of the polymer products. Isobutane present in propylene in amounts as small as 1% by volume reduces the thickening power of the product by as much as 25%. The art, bridging columns 1 and 2 of '957, is cited as disclosing highly viscous polymers of monoalkylethylenes produced by the polymerization in the presence of aluminum bromide and hydrogen bromide through the concurrent use of specified molar ratios of promoter to dissolved aluminum catalyst.
U.S. Pat. No. 3,159,607 is directed to catalysts for the polymerization of olefins and substituted olefins. Suitable olefins disclosed include butene-1 and isobutylene. The catalysts disclosed include aluminum halide, specifically aluminum chloride, aluminum bromide, and organo aluminum compounds at concentrations ranging from 0.001 to 0.1 moles. The polymerization temperature ranged from -75.degree. C. to 200.degree. C. The pressures are from one atmosphere up to 10,000 psi. Example 1 discloses the production of polybutene using aluminum chloride, triisobutyl aluminum and toluene.
U.S. Pat. No. 3,833,678 is directed to stabilized solutions of aluminum chloride or aluminum bromide in molar excess, in methyl esters of certain normal and branched chain alkanoic acids.
U.S. Pat. Nos. 4,229,611 and 4,162,233 disclose the isomerization of various hydrocarbons by aluminum bromide and other super-acid type materials. Lewis acids are disclosed which are characterized as being capable of stabilizing high concentrations of tertiary cations, e.g. t-butyl cation and further characterized as capable of forming carbonium ion salts containing both dimeric and monomeric anions. The ions undergo hydride and halide exchange with other alkanes and halides. It is disclosed that pure, dried aluminum bromide is not an effective catalyst unless the system contains some trace of alkyl halide, alcohol or combination of an alkene and a protein source. Promoters include hydrogen halides, alkyl halides and water.
U.S. Pat. No. 4,533,782 discloses a process for polymerizing cationically polymerizable monomers using a solution containing an activated catalyst. The catalyst comprises:
a) an aluminum compound having the formula R.sub.n AlX.sub.3-n, wherein n is an integer from 0 to 3; R is C.sub.1 to C.sub.12 alkyl, C.sub.7 to C.sub.9 aralkyl, C.sub.7 to C.sub.18 alkaryl or C.sub.6 to C.sub.10 aryl; and X is Cl, Br or I; and PA1 b) (1) a compound having the formula R'X, wherein X is Cl, Br or I and R' is C.sub.1 to C.sub.24 alkyl, C.sub.3 to C.sub.20 alkenyl, C.sub.5 to C.sub.9 bridged or non-bridged cycloalkyl or cycloalkenyl, C.sub.7 to C.sub.9 aralkyl or (2) a hydrocarbon polymer carrying at least one X substituent wherein X is Cl, Br or I.
U.S. Pat. No. 5,068,476 is directed to liquid olefin oligomers produced by the oligomerization of C.sub.2 to C.sub.5 alpha-olefin alone or with ethylene as a comonomer. The oligomers have a high viscosity index and a structure which is characterized by a regio-irregularity of at least 20%, usually from 20 to 40%. The molecular weight of the oligomers can range from 250 to 100,000. The olefins are oligomerized with a reduced valance state chromium oxide catalyst on a silica support, usually at a temperature from 90.degree. C. to 250.degree. C. The liquid oligomerization products can be produced in a wide range of viscosities including the direct production of low viscosity lubricants having high viscosity index.
U.S. Pat. No. 4,948,522 is directed to a dispersant additive package for cylinder lubricants for marine diesel engines. The package comprises a borated dispersant and a high molecular weight polybutene. Preferred polybutenes are disclosed to have a weight average molecular weight of greater than 200,000, more preferably greater than 500,000 and most preferably polybutenes of an average molecular weight of 400,000 to 3,000,000 are used.
U.S. Pat. No. 4,952,739 is directed to organo aluminum chloride catalyzed poly-n-butenes. Poly-n-butenes are prepared from a mixed C.sub.4 hydrocarbon feedstream which comprises less than about 5% isobutylene and at least about 12% normal butenes together with n-butane, isobutane and less than about 1% butadiene. Streams of this type are commonly referred to as Raffinate II. In accordance with the disclosure, aluminum chloride catalyst was used to prepare poly-n-butene having a number average molecular weight range of about 300 to about 900.
"Utilization of Waste C.sub.4 -fraction from Petrol Chemical Manufacturing in the Preparation of Alkenyl-Succinimides from Low Molecular Weight Poly-n-butenes", Marek et al., Chemical Industry, vol. 40-85 (1990), No. 1 discloses low molecular weight poly-n-butene polymers made from Raffinate II.
European Patent Publication No. 0,337,737 discloses the polymerization of olefins in a Raffinate II composition containing 1-butene, and trans-2-butene with BF.sub.3 or alkyl aluminum chlorides in the presence of HCl, HF or organic compounds with a reactive chlorine or fluorine bonded to a tertiary-, benzyl- or allyl carbon atom as co-initiators. The method is conducted in the presence of at least 20% 1-butene, and at least 15% 2-butene, at from -70.degree. C. to +100.degree. C. The resulting polymer has a number average molecular weight of 300 to 1,200.
European Patent Publication No. 0,369,674-B1 discloses oil soluble viscosity index improver-dispersant additives comprising poly-n-butene substituted carboxylic acid material. The poly-n-butene is disclosed to have a number average molecular weight of from about 300 to 3,000. More particularly, there is disclosed an oil soluble viscosity index improver-dispersant additives comprising the reaction products of (i) ethylene copolymers, such as copolymers of ethylene and propylene, grafted with ethylenically unsaturated carboxylic acid moieties, preferably maleic anhydride moieties; (ii) polyamines having two or more reactive amine groups selected from primary and secondary amine groups, or polyols; and (iii) poly-n-butene substituted carboxylic acid material wherein the poly-n-butene has a number average molecular weight of from about 300 to 3,000. The multifunctional viscosity index improvers containing the poly-n-butene substituted dicarboxylic acid material when incorporated into oleaginous compositions such as lubricating oil compositions, result in oil compositions exhibiting improved, low temperature viscosity characteristics.
Other references of interest include U.S. Pat. Nos. 2,521,940; 2,631,176; 3,497,568; 3,501,551; 3,749,560; 3,932,371; 3,985,822; 4,419,503; 4,465,887; 4,883,847 and GB 1,325,701.